Open new Window directly from Menubar

[Photatum]

Hey there,
new here and not that long into C++ and especially QT.
I searched some time, but couldn't find an answer, that related to my problem:

I want to open a new window directly from a button (QMenu) in the menubar, not by choosing QAction in a dropdown list.

I tried this like I would with a QAction in the dropdown list but when I click on the button, nothing happens except that the button appears 'clicked'.
@
...
connect(ui->menuBenchmark, SIGNAL(triggered(QAction*)), this, SLOT(benchmark()));
// menuBenchmark is of type QMenu
...

void MainWindow::benchmark()
{
BenchmarkWindow* window = new BenchmarkWindow();
window->show();
}
@

I don't get any errors so I really don't know what I'm doing wrong or what equivalent I should use for QMenu instead of QAction.
The window itself opens fine when I call it from a dropdown list, so I guess there's something wrong with connect and QMenu.

Hope, someone can help me with this.
Regards,
Photo